SS-31 (Elamipretide): Legal Status and Forzinity

Legal status of SS-31 (elamipretide)

FDA-approved drug

Elamipretide is FDA-approved as Forzinity, only for Barth syndrome in patients weighing at least 30 kg ^[1]. SS-31 sold online as a research chemical is not Forzinity ^[2].

FDA status

FDA granted accelerated approval to Forzinity (elamipretide) on Sept 19, 2025 ^[1]. It is the first treatment for Barth syndrome, in patients weighing at least 30 kg ^[1]. The approval was based on improved knee muscle strength ^[1]. FDA sent warning letters in August 2026 to sellers of "research use only" SS-31 ^{[2] [3]}.

Advisory committee

Not applicable. Elamipretide is an FDA-approved drug ^[1].

FDA-approved products

Forzinity (elamipretide), approved Sept 19, 2025 ^[1]. Reuters reported a price of up to nearly $800,000 a year ^[5].

Sports (WADA)

Elamipretide is not named on the 2026 list ^[9].

What happens next

Nothing. A doctor can prescribe Forzinity now for its approved use ^[1].

Checked against FDA sources on Oct 24, 2026. We update this box when FDA acts. Report a change: [email protected].

Forzinity: approved for one rare disease

FDA describes Barth syndrome as "a rare, serious and life-threatening disease of the mitochondria," the energy-producing parts of cells, which mainly affects males ^[1]. Forzinity is "the first treatment for Barth syndrome, in patients weighing at least 30 kg" ^[1]. Its label indication is "to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg" ^[4].

The maker, Stealth BioTherapeutics, announced on June 16, 2026 that it now operates as Mighty Therapeutics ^[6].

What accelerated approval means here

FDA based Forzinity's accelerated approval on "improved strength of the muscle used to straighten the leg at the knee" ^[1]. The maker must run a randomized, double-blind, placebo-controlled trial after approval to show that the strength gain translates into benefit for patients ^[1]. The label says continued approval may depend on that confirmation ^{[4] [6]}.

Reuters reported in November 2025 that FDA cleared the drug over reviewer objections ^[5].

Safety facts from the label

• Do not use with a serious allergy to elamipretide or any ingredient in Forzinity ^[4].
• Allergic reactions. Serious reactions needing emergency care have been reported, from minutes to months after starting ^[4].
• Benzyl alcohol. Forzinity is not approved for newborns, because benzyl alcohol in drugs has caused serious and fatal reactions in premature and low-birth-weight infants ^[4].
• Injection site reactions are the most common side effect. In the label's placebo-controlled crossover study of 12 patients, all 12 had a local reaction on elamipretide; injection site pain affected 75% ^[4].

Price and insurance

Forzinity is a prescription drug for diagnosed Barth syndrome. Reuters reported a price of up to nearly $800,000 a year; we found no list price on the maker's materials we reviewed ^[5].

Insurers set strict rules. One Medicaid plan's 2026 policy, for example, requires Barth syndrome confirmed by genetic testing for a TAZ gene mutation, weight of at least 30 kg, and a prescriber who is or consults a specialist such as a clinical geneticist or metabolic disease specialist; it approves 6 months at first and 12 months on renewal ^[7]. Uses outside the FDA-approved indication go through a separate off-label review ^[7].

Other peptides with a legal route are on our legal peptide price tracker.

Research-use SS-31 is not Forzinity

Online, SS-31 is sold in vials labeled for research. Those products are not Forzinity and have no FDA approval. On Aug 24, 2026, FDA sent warning letters to Royal Peptides LLC and Peptide Partners LLC for selling unapproved drugs, including SS-31 (elamipretide), with labels such as "for research use only" ^{[2] [3]}. FDA rejected that labeling as a defense in an earlier letter too ^[8].

Forzinity's approval does not extend to longevity or fitness use. Its evidence comes from people with Barth syndrome, and its label safety data come from a small study ^[4].

Elamipretide and anti-doping rules

Elamipretide is not named on the 2026 WADA Prohibited List ^[9]. Athletes should still ask their anti-doping agency before using any new drug.

Dated changes

• Aug 24, 2026: FDA sent warning letters to online sellers of research-use SS-31 and other peptides ^{[2] [3]}.
• Sep 19, 2025: FDA granted accelerated approval to Forzinity for Barth syndrome ^[1].

Related pages: our peptide FDA status tracker, PT-141, another approved peptide, tesamorelin, FDA warning letters, our longevity guide and NAD injections, another product marketed for mitochondrial health, and thymosin alpha-1.

The other FDA-approved peptide drug with its own page here: PT-141. Unapproved peptides with pending reviews include GHK-Cu, epitalon and TB-500.

How we check

Approval facts come from FDA's announcement and the label text ^{[1] [4]}. We rechecked them, and searched for newer approvals or label changes, on Oct 24, 2026. We do not link to research chemical sellers. See our editorial standards.